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ChemicalEngineeringThermodynamicsDeterminationandCorrelationofSolubilityofNonivamideinDifferentSolvents☆YifengCao,QiweiYang,HuabinXing⁎,ZongbiBao,BaogenSu,YiwenYang,QilongRenKeyLaboratoryofBiomassChemicalEngineeringofMinistryofEducation,DepartmentofChemicalandBiologicalEngineering,ZhejiangUniversity,Hangzhou310027,ChinaabstractarticleinfoArticlehistory:Received20December2012Receivedinrevisedform13April2013Accepted6May2013Availableonline4September2014Keywords:SolubilityNonivamideHydrogen-bondinginteractionModifiedApelblatequationvan'tHoffplottingThesolubilityofnonivamideindimethylsulfoxide,methanol,acetone,ethylacetate,methyltert-butylether,ace-tonitrile,n-hexaneandwateroverthetemperaturerangeof293.2Kto323.2Kwasmeasured.Theresultsrevealthatthesolubilityofnonivamideisgreatlyinfluencedbythehydrogen-bondbasicityofsolventandincreaseswithtemperature.TheexperimentaldatawerecorrelatedwiththemodifiedApelblatequation.Thedissolutionenthalpyandentropyofnonivamideindifferentsolventswereobtainedfromthecorrelationoflnxwith1/Tusingthevan'tHoffequation.Thecalculatednonivamidesolubilityisingoodagreementwithexperimentaldataformostofthesolvents.©2014TheChemicalIndustryandEngineeringSocietyofChina,andChemicalIndustryPress.Allrightsreserved.1.IntroductionNonivamide(CASRegistryNumber2444-46-4,molecularweight293.4,Fig.1)isaminorconstituentofcapsicumoleoresin[1].Itshowsmanybiologicalandpharmacologicaleffects,suchasantibac-terial,anti-inflammatory,andanalgesic[2–4].Itisconsideredasanalternativeofcapsaicin,becauseitissimilartocapsaicinstructurallyandbiologically[5],andcouldbeeasilymanufacturedsynthetically,costinglessthanthenaturalcapsaicinisolatedfromcapsicum.Thesolubilityofnonivamideinsolventsisofgreatimportanceforsepa-rationandpurificationofnonivamide.However,asfarasweknow,noexperimentalsolubilitydataofpurenonivamideinorganicsol-ventsorwaterhavebeenreported.Inthisstudy,thesolubilityofnonivamideineightsolventsoverthetemperaturerangeof293.2Kto323.2Kwasmeasured,includingpolaramphiproticsolventmethanol,polaraproticsolventsdimethylsulfoxide(DMSO),acetone,ethylacetate,acetonitrileandmethyltert-butylether(MTBE),non-polaraproticsolventn-hexane,andhighlypolarsolventwater.Theexperimentalsolubilitydatawereexplainedonthebasisofthesolvatochromicparametersofthesol-ventsandcorrelatedwiththemodifiedApelblatequationandthevan'tHoffequation.2.Experimental2.1.MaterialsNonivamidewasobtainedfromHangzhouGreatForestBiomedicalLtd.(China),withpurityhigherthan99.6%[HighPerformanceLiquidChromatography(HPLC)].Methanol,acetone,ethylacetate,MTBE,acetonitrileandn-hexanewerepurchasedfromTedia(USA)andwereofHPLCgradewithamassfractionover99.5%.DMSOwaspurchasedfromSinopharmChemicalReagentCo.,Ltd.(China)andwasofanalyti-calgradewithamassfractionover99.0%.Thedeionizedwaterwasob-tainedfromHangzhouWahahaGroupCo.,Ltd.(China).2.2.ApparatusandprocedureThesolubilitiesofnonivamideinDMSO,methanol,acetone,ethylac-etate,methyltert-butyletherandacetonitrileweredeterminedbyady-namicmethod[6].Theexperimentswerecarriedoutinamagneticallystirred,jacketedglassvessel(about15cm3).Aconstanttemperaturewasmaintainedbycirculatingwaterthroughtheouterjacketfromathermostaticallycontrolledbath(uncertaintyof±0.1K).Theactualtemperatureinthevesselwasmeasuredbyamicrothermometerwithanuncertaintyof±0.01K.Forsolubilitymeasurements,predeterminedmassofnonivamidewasweighedbyanelectronicbalancewithanac-curacyof±0.0001gandtransferredintothevessel.Thesolventwasaddeddropwisetothevesselintheearlystageoftheexperiment,andtowardstheendofexperiments,10μlsolventwasaddedtothevesseleachtimeuntilthesolutewascompletelydissolved,whichwasChineseJournalofChemicalEngineering22(2014)1141–1144☆SupportedbytheNationalNaturalScienceFoundationofChina(20936005,21222601)andtheNationalHighTechnologyResearchandDevelopmentProgramofChina(2012AA040211).⁎Correspondingauthor.E-mailaddress:xinghb@zju.edu.cn(H.Xing).©2014TheChemicalIndustryandEngineeringSocietyofChina,andChemicalIndustryPress.Allrightsreserved.ContentslistsavailableatScienceDirectChineseJournalofChemicalEngineeringjournalhomepage:flask.Then,thetotalmassofthesampleandflaskwasweighedusingtheelectronicbalance.Afterthat,thesamplewasdilutedwithmethanolforHPLCanalysis.Forverylowsolubilitiesofnonivamideinhexaneandwater,thedy-namicmethodwasnotapplicableandthestaticequilibriummethodwasused.Theprocedurewasdescribedinourpreviouswork[7,8].Theexperimentswerecarriedoutinamagneticallystirred,jacketedglassvessel(about150cm3),inwhichthetemperaturewascontrolledtobeconstantbycirculatingwaterthroughtheouterjacketfromathermo-staticallycontrolledbath(uncertaintyof±0.1K).Amicrothermometerwasusedtomeasuretheactualtemperatureinthevesselwithanuncertaintyof±0.01K.Foreachmeasurement,anexcessmassofnonivamidewasaddedtoaknownamountofsolvent.Topreventsol-ventvolatilization,acold-w